package in.hooray.core.mybatis.plugin;

import in.hooray.core.mybatis.dialect.Dialect;

import java.util.Properties;

import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.SqlSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;



//@Component
@Intercepts({ @Signature(type = Executor.class, method = "query", args = {
		MappedStatement.class, Object.class, RowBounds.class,
		ResultHandler.class }) })
public class PagingPlugin implements Interceptor {
	private String dialectClass;

	public void setDialectClass(String dialectClass) {
		this.dialectClass = dialectClass;
	}

	final static int MAPPED_STATEMENT_INDEX = 0;
	final static int PARAMETER_INDEX = 1;
	final static int ROWBOUNDS_INDEX = 2;
	final static int RESULT_HANDLER_INDEX = 3;

	Dialect dialect;

	public Object intercept(Invocation invocation) throws Throwable {
		processIntercept(invocation.getArgs());
		return invocation.proceed();
	}

	void processIntercept(final Object[] queryArgs) {
		if(dialectClass!=null){
			this.setDialect(dialectClass);
		}
		MappedStatement ms = (MappedStatement) queryArgs[MAPPED_STATEMENT_INDEX];
		Object parameter = queryArgs[PARAMETER_INDEX];
		final RowBounds rowBounds = (RowBounds) queryArgs[ROWBOUNDS_INDEX];
		int offset = rowBounds.getOffset();
		int limit = rowBounds.getLimit();

		if (dialect.supportsLimit() && 
				(offset != RowBounds.NO_ROW_OFFSET || limit != RowBounds.NO_ROW_LIMIT)) {
			BoundSql boundSql = ms.getBoundSql(parameter);
			String sql = boundSql.getSql().trim();
			if (dialect.supportsLimitOffset()) {
				sql = dialect.getLimitString(sql, offset, limit);
				offset = RowBounds.NO_ROW_OFFSET;
			} else {
				sql = dialect.getLimitString(sql, 0, limit);
			}
			limit = RowBounds.NO_ROW_LIMIT;

			queryArgs[ROWBOUNDS_INDEX] = new RowBounds(offset, limit);
			BoundSql newBoundSql = new BoundSql(ms.getConfiguration(), sql,
					boundSql.getParameterMappings(),
					boundSql.getParameterObject());
			
			for (ParameterMapping mapping : boundSql.getParameterMappings()) {
                String prop = mapping.getProperty();
                if (boundSql.hasAdditionalParameter(prop)) {
                    newBoundSql.setAdditionalParameter(prop, boundSql.getAdditionalParameter(prop));
                }
            }
			
			MappedStatement newMs = copyFromMappedStatement(ms,
					new BoundSqlSqlSource(newBoundSql));
			queryArgs[MAPPED_STATEMENT_INDEX] = newMs;
		}
	}

	private MappedStatement copyFromMappedStatement(MappedStatement ms,SqlSource newSqlSource) {
		MappedStatement.Builder builder = new MappedStatement.Builder(
				ms.getConfiguration(), ms.getId(), newSqlSource,ms.getSqlCommandType());

		builder.resource(ms.getResource());
		builder.fetchSize(ms.getFetchSize());
		builder.statementType(ms.getStatementType());
		builder.keyGenerator(ms.getKeyGenerator());
		//builder.keyProperty(ms.getKeyProperty());
		builder.timeout(ms.getTimeout());
		builder.parameterMap(ms.getParameterMap());
		builder.resultMaps(ms.getResultMaps());
		builder.cache(ms.getCache());
		MappedStatement newMs = builder.build();
		return newMs;
	}

	public Object plugin(Object target) {
		return Plugin.wrap(target, this);
	}

	public static class BoundSqlSqlSource implements SqlSource {
		BoundSql boundSql;

		public BoundSqlSqlSource(BoundSql boundSql) {
			this.boundSql = boundSql;
		}

		public BoundSql getBoundSql(Object parameterObject) {
			return boundSql;
		}
	}

	public void setProperties(Properties properties) {
		if (dialectClass == null) {
			dialectClass = properties.getProperty("dialectClass");
		}
		this.setDialect(dialectClass);

	}
	
	private  void setDialect(String dialectClass){
		try {
			dialect = (Dialect) Class.forName(dialectClass).newInstance();
		} catch (Exception e) {
			throw new RuntimeException("cannot create dialect instance by dialectClass:"+ dialectClass, e);
		}
		System.out.println(PagingPlugin.class.getSimpleName() + ".dialect="+ dialectClass);
	}

}
